Technical Field
This invention relates generally to image projection systems and methods, and more particularly to image projection systems and methods that improve highlights in projected images.
Description of the Background Art
Video projection systems for use in movie theaters (cinemas) and home theaters are known. While home theater systems usually are capable of displaying only two-dimensional (2D) images, projection systems in movie theaters are often capable of displaying three-dimensional (3D) video. 3D projection systems are very complex and thus expensive. They represent a significant capital investment for the cinema, especially if the 3D projection system is being used to show both 3D and 2D films and is operating in 2D mode a significant portion of the time.
It is also a goal of all projection systems to provide realistic imagery. An important component in realizing this goal is increasing the peak brightness capable of being produced in the projected imagery. For example, most images will include both regions that are very bright (e.g., the sun) and areas that are very dim (e.g., objects in a shadow). Projections systems that have low peak brightness are not able to represent such scenes very realistically, because the bright regions do not appear bright enough to the viewer. Brightness can be increased by adding a separate highlight projector to the projection system. However, the highlight projector represents a significant additional cost to the movie theater, especially in view of the already-expensive 3D projection systems, which often require multiple projectors. Furthermore, the highlight projector must remain aligned with the main projector(s) for the highlighted images to appear realistic and undistorted, which adds yet another on-going maintenance cost and time burden on the movie theater.